1. Field of the Invention
The present invention relates generally to methods and apparatus for soot radial pressing for optical fiber overcladding, and particularly to methods and apparatus for making optical fiber preforms.
2. Technical Background
Conventional chemical vapor deposition (CVD) processes, such as outside vapor deposition (OVD) and vapor axial deposition (VAD) processes, for making optical fiber preforms often utilize only a portion of the starting raw material due to limitations in the deposition efficiency of the OVD process. Use of the resulting “waste” silica soot could, therefore, potentially result in significant raw material cost savings.
Accordingly, different methods have been devised to utilize otherwise unutilized silica soot in the production of optical fiber preforms. These methods, which include, for example, axial pressing, sol-gel (and other “wet”) processes can suffer from a variety of drawbacks including expensive, complicated, and/or time consuming processing conditions and equipment, and may result in preforms with less than desirable properties such as unacceptable variability with respect to preform density and geometry.